On Tue, Nov 21, 2023 at 03:20:08PM -0600, Nathan Bossart wrote: > * Overhead: The wrapper handler calls a function pointer and getpid(), > which AFAICT is a real system call on most platforms. That might not be > a tremendous amount of overhead, but it's not zero, either. I'm > particularly worried about signal-heavy code like synchronous > replication. (Are there other areas that should be tested?) If this is > a concern, perhaps we could allow certain processes to opt out of this > wrapper handler, provided we believe it is unlikely to fork or that the > handler code is safe to run in grandchild processes.
I finally spent some time trying to measure this overhead. Specifically, I sent many, many SIGUSR2 signals to postmaster, which just uses dummy_handler(), i.e., does nothing. I was just barely able to get wrapper_handler() to show up in the first page of 'perf top' in this extreme case, which leads me to think that the overhead might not be a problem. -- Nathan Bossart Amazon Web Services: https://aws.amazon.com